Snap action device



June 2, 942. A E BAAK I 2,284,911() SNAP ACTION DEVICE Filed Aug. 4, 1939 i ,'nvmfor Alberi' E7 Baak.

Patented June 2, 1942 SNAP ACTION DEVICE Albert E. Baak, Minneapolis, Minn., assigner to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application August 4, 1939, Serial No. 288,255 (Cl. 20o- 83) 21 Claims.

This invention relates broadly to snap action mechanisms and more particularly to snap action mechanisms which are operated automatically in response to changes in a variable condition. Snap action mechanisms inherently have a certain di'erential of operation and the present inv vention deals particularly with the adjustment of the limits of this dierential.

The primary object of the invention is to provide a mechanical snap action mechanism Ain which the two ,limits of the differential are adjustable independently of each other.

A further object is to provide a control device which may be biased in one direction against one latch and in the other direction against a second latch in combination with a condition responsive device for alternately. tripping the latches.

These and other objects will become apparent as the following specification is read in the light oi the accompanying drawing in which Figure 1 is a more or less diagrammatic view of the snap action mechanism of my invention, and l Figure 2 is a view similar to Figure 1 showing the parts in a different position.

A casing is provided as indicated at III for housing the snap action mechanism. Mounted within the casing and at the bottom thereof is a bracket II which pivotally carries a lever I2 as indicated at I3. The lever I2 carries a resilient contact blade I4 and a rigid stop arm I5 by means spring I9 whose other end is hooked into the bracket II to bias the lever I2 for rotation in a counter-clockwise direction. A lso mounted at the bottom of the casing Il is a bracket 20 which is provided at its upper end with a forwardly extending arm 2l which carries a stationary electrical contact 22 with which the movable contact I'I is adapted to engage.

Connected to the side of the casingY I is a bracket 25 which pivotally supports a latch 26 as indicated at .21. The bracket 25 also carries a leaf spring 28 having a. curved end 23 which engages the latch 26 and biases it for rotation in a clockwise direction. Attached to the opposite side of casing I0 is another bracket 3l which pivotally carries the latch 3i as indicated at 32. Bracket. also carries a leaf spring 33 engaging the latch 3i and biasing it for rotation in a counter-clockwise direction.

A iloating switch actuating lever is indicated at 35. Although no such means has been illustrated, it will be understood that some device is used in connection with this floating lever to prevent it from moving laterally with respect to the casing I0. A second pivoted lever such as is disclosed in applicants Patent No. 2,266,144 of Dec. 16, 1 941, may be used. The lever 35 is provided withan upwardly projecting ear 36 near its end 3'I to which is connected one end of a tension spring 38, the other end of the spring being secured to an adjusting nut 33 whichls screwthreadedly mounted on the screw 40. Screw 4I projects loosely through the hole 4I in the top of the casing I0 and is provided with a ilangedhead 42 having a kerf 43 by meansnil which it may be rotated. The nut 33 is provided with an outwardly extending arm 44 which projects through a slot 45 in the side of the casing III to prevent rotation of the nut 1J as the screw 4I) is rotated. As a result of this construction, rotation of the screw 40 will vertically adjust the nut 33 and hence adjust the tension of the spring 33. If desired a scale may be applied to the outside of the casing Ill adjacent the slot 45 in order to indicate the adjustment of the spring 33.

The end 41 of lever 35 is provided with an ear 43 to which one end of spring 49 is connected The other end of this spring is secured to the 4adjusting nut 5I) which is screw-threadedly mounted on the screw 5I. The screw 5I projects loosely through the hole 52 in the top of the casing Il and is provided with a flanged head 5l having a kerf 54. The nut SII is provided with an arm projecting outwardly through slot 55 in the side of casing III. The spring 43 is therefore adjusted by the screw 5I in the same manner as the spring 33 and a scale may be applied to the outside of thecasing I l adjacent the slot 56 to indicate the adjustment of the spring 49. The springs 38 and 43 normally hold the lever 35 in its upper position adiacent the stops 5I and 53 as seen in Figure 2. .y

Suspended from the top of casing Il is a bellows 6l which is connected by means of a capilby the mid portion of the lever 35. 0n expansion of the bellows. the lever 3l is moved downwardly and this pomtion is limited by means of the stops i u and u. j

'l2 which under Vcertain circumstances engages the shoulder 13 on the latch 3 I In considering the operationof the above described device, let it be assumed first that the temperature or pressure to which the bellows 6I! responds is at a predetermined low value and that the bellows I) is in its contracted position as shown in Figure 2. Under these circumstances, the adjusting springs 39 and 49 will hold the lever` 35 in engagement with the stops 53 and 59. It will be seen that at this time the end 31 of the lever 35 has cammed the latch 26 to its inoperative position and that the end 41 of lever 35 has disengaged the latch 3l and the spring 33 has rotated this latch until it isin a position where the end 12 on the resilient lcontact blade I4 may engage the shoulder 13 of the latch whenl the lever I2 is rotated in a clockwise direction. It will be further noted that the biasing spring I9 has rotated the lever I2 to the position where the contacts I1 and 22 are in open circuit position. The rotation of the lever I2 under the influence oi the spring I9 is limited by the stop 15. In order for this mechanism to function in the desired manner, the spring 49 must exert a greater force than the spring 38.

Under these circumstances as the bellows 60 begins to expand in response to an increase in temperature or pressure, it will ilrst rotate the lever 35 in a clockwise direction so that the end 31 will leave the stop 59 against the force exerted by the spring 39. This will release the latch 26 which will then be rotated in a clockwise direction by means of its biasing-spring 28. As the end 31 of the lever 35 continues to move downwardly, the insulating pusher 69 will engage the .extension 10on the lever I2 and rotate the lever to its circuit closed position. The stop 65 will prevent further movement of the end 31. At this time, the end 12 of the resilient contact blade I4 will have engaged the shoulder 13 of the latch 3| Y 'which will prevent the closure of the contacts I1 biasing spring I9 to snap the lever in a counter'- clockwise direction opening the contacts I1 and 22 and returning the parts to the position shown in Figure 2.

The temperature or pressure value at which the end 31 of the lever 35 4is moved downwardly and upwardly by the bellows 60 is determined entirely by the tension of the spring 38. The adjustment of the spring 49 does not affect this operation materially due to the fact that when the end 31 is being moved the lever 35 is pivoting about the stop 59 which is located so close to the ear 43 to which the spring 59 is connected to the lever 35 that the force exerted by this spring has substantially no rotative eect upon the lever 35. It will be seen in connectionwith the description of the operation o! `this device that the movement of the end 31 causes opening of the switch contacts I1 and 22. Therefore by adjusting the spring 39 the temperature or pressure value at which the switch is openedmay be adjusted.

Likewise. the temperature or pressure value at which the end 41 is moved is determined entirely by the adjustment of the tension oi' the spring 49. Movement of this end of the lever 35 controls the closing of the contacts I1 and 22. Therefore by adjusting the tension of the spring 49, the temperature or pressure value at which these contacts are closed may be independently varied.

It will therefore be seen that I have provided a switch which is opened and closed by means of a mechanical snap action wherein the temperature or pressure values at whichA the switch is opened may be independently varied as well as the temperature or pressure values at which the switch is snapped closed.

As certain changes and modifications of this invention will occur to those who are skilled in the art, I wish it to be understood that I am to be limited by the scope of the appended claims and not by the specific embodiment disclosed.

I claim as my invention:

1. A snap action device comprising in combination, a control member, a iirst means for biasing said control member for movement in one direction, a first holding device preventing such movement, a second means for biasing said conb'lade I4 permitting the contacts I1 and 22 to close with a snap action. The end 41 will continue to move downwardly until it engages the stop 69 as shown in dotted lines in Figure l.

On a decrease in the temperature or pressure to which the bellows 90 responds, it will contract andraise the end 41 of the lever 35 releasing the latch 3i. This movement of the lever 35 has no effect upon the switch contacts I1 and 22. Further contraction of the bellows will raise the Yend 31 of the lever 35 which will raise the pusher 69 and permit the extension 10 of the lever Il to engage the shoulder 1I von the latch 26 thereby preventing the lever I2 from rotating in a direction to cause the disengagement of the contacts I1 and 22. On further upward movement the end 31 will cam the lever 26 in a counterclockwise direction until the shoulder 1I releases the extension 10 of the lever I2 permitting the I5 trol member formovement in the other direction, a second holding device for preventing such movement, and condition responsive means for alternately Vtensioning said biasing means and releasing said holdlng devices.

2. A snap action device comprising in combination, a control member, a rst means for biasing said control member for movement in one direction, a `first holding device preventing suchl movement, a second means for biasing said control member for movement in the otherdirection,

a second holding device for preventing such movement, condition responsive means for alternately tensioning said biasing means and releasing said holding devices, and means for adjust- .ing the differential of operation oi' said snap action device.

3. A snap action device comprising in combination, a control member, a ilrst means for blasing said control member for movement in one direction, a first holding `device preventing such movement, a second means for biasing said control member for movement in the other direction. a second holding device for preventing auch movement, condition responsive means for alternately tensioning said biasing means and releasing said holding devices whereby said control trol device in one direction with member is snapped nrst in one direction and then the other, and means for individually and independently varying the condition value1/at which said control member is snapped in each direction. i

4. A snapaction device comprising inv combination, an actuating member, a condition responsive device associated with saidl member to move first one end and then the other end ofsaid actuating member, a con-trol device, a. mechanical snap action device actuated by one end of said actuating member for moving said control device in one direction with a snap'action, means preventing -the return of said control device to its original position, and means actuated by the.n

other end of said actuating member for disabling ,f

said last mentioned means.

5. A snap action device comprising in combination, an actuating membera condition responsive device associated with said member to move first one end and then the other end of said actuating member, a control'device, a mechanical snap action device actuated by one end of said actuating member for moving said control device in one direction with a snap action, and means controlled by the other end of said actuating member for returning said control device to its original position.

6. A snap action device comprising in combination, an actuating member, a condition responsive device associated with said member to move first one end and then the other end of said actuating member, a control device, a mechanical snap action device actuated by one end of said actuating member for moving said control device in one direction with a snap-action, and snap action mechanism controlled by the other end of said actuating member for returning said control device to its original position with a snap action.

7. A snap action device comprising in combination, an actuating member, a condition responsive device associated with said member to move first one end and then the other end of said actuating member, a control device, a mechanical snap action device actuated by one end of said actuating member for moving said control device in one direction with a snap action, means preventing the retllln of said control device to its original position, means actuated by the other end of said actuating member for disabling said last mentioned means, and means for independently adjusting the condition value at which each end of said actuating member is moved by said condition responsive device.

8. A snap action device comprising in combination, an actuating member, a `rcondition responsive device associated with said member toy lmove rst one end and then the other end of said actuating member, a control. device, a mechanical snap action device actuated by one end of said actuating member for moving said cona snap action, means controlled by the other end of said actuating member .for returning said control device to its original position, and means for independently adjusting the condition value at which each end of said actuating member condition responsive device.

9. A snap action device comprising in combination, an actuating member, a condition re-v sponsive device associated with said member to move iirst oneend and then the other end of said actuating member, a control device, a mechanical snap action device actuated by 'one end of said actuating member for moving said control device in one direction with a snap action, snap action mechanism controlled by the other end of said actuating member for returning said control device to its original position with a snap action, and means for independently adjusting the condition value at which each end of said actuating member is moved by said condition responsive device. l

l0. A device of the character described comprising in combination, a movable member, va movable contact carried thereby by means of a resilient mounting, a stationar contact positioned to be engaged by said movable contact, means continuously biasing said movable member to contact open position, means for moving said member to contact closed position against the action of said biasing means, a first latch for holding said movable contact in open position by pressing back its resilient mounting, a

closed position, and means for tripping said iirst latch and then said second latch.

l1. A device of the character described comprising in combination, a movable member, a movable contact carried therebyby means of a resilient mounting. a stationary contact positioned to be engaged by said movable contact, means continuously biasing said movable member to contact open position, means for moving said member to contact closed position against the action of said biasing means, a rst latch for holding said movable contact in open position by pressing back its resilient mounting, a second latch for holding said member in contact closed position, means for tripping said iirst latch and then said second latch, said last named means being actuated by a condition responsive device, and means; for varying the differential between the condition values at which each latch is tripped.

tocontact open position, means for moving said lmember to contact closed position against the action of said biasing means, a iirst latch for holding said movable contact in open position by pressing back its resilient mounting, a second i latch for holding said member in contact closed is moved by said f contact resiliently carried thereby,

position, means for tripping said iirst latch and then said second latch. said last named means being actuated by a condition responsive device,

and means for individually adiusting the condition` value atwhich each latch is'tripped.

13. An automatic switching device comprising in combination, a movable member, a movable a rstationary contact adapted to be engaged by said movable contact, means biasing said member to contact open position, an actuating member, a condition responsive device for first moving one end of said actuating member in response-to a change in the condition value which moves said movable member against its bias and latches it ony a ilrst latch, and a second latch for holding said movable contact in open position against the force exerted by its resilient mounting, a further change in said' condition value causing said condition responsive device to move the other end of said actuating .member to trip said second Alatch and hence close said contacts, a reversal in said condition change causing 4said condition responsive devicelto first move the said other end of said actuating member and then the said one end to trip said first latch and permit said movable member to move to open'contact position under the influence of its bias.

14. An automatic switching device comprising in combination, a' movable member, a movable contact resiliently carried thereby, a stationary contact adapted to be engaged by said movable contact, means biasing said member to contact open position, an actuating member, a condition responsive device for first moving one end of said actuating member in response to a change in the condition value which moves said movable member against its bias and latches it on a iirst latch, and a second `latch 'for holding said movable contact in open position against the force exerted by its resilient mounting, a further change in said condition value causing said condition responsive device to move the other end of said actuating member to trip said second latch and hence close said contacts, a reversal in said condition change causing said condition responsive device to rst move the said other end of said actuating member and then the said one end to trip said first latch and permit said movable member to move to open contact position under the influence of its bias, and means for varying the difference between the condition values at which each end of said actuating memberis moved. l

15. An automatic switching device comprising in combination, a movable member, a movable contact resiliently carried thereby, a stationary contact adapted to be engaged by said movable contact, means biasing said member to contact open position, an actuating member, a condition responsive device for first moving one end of said actuating member in response to a change in the condition value which `moves said movable member against its bias and `latches it on a rst latch, a second latch for holding said movable contact in open position against the' force exerted by its resilient mounting, a further'change in said condition value causing said condition responsive device to move the other end of said actuating member to trip said second latch and hence close said contacts, a reversal in said condition change causing said condition responsive device to first move the said other end of said actuating member and then the said one end to trip said iirst latch and permit said movable member to move to open contact position under the iniluence of its bias, and spring means for individually adjusting the condition value at which each end of said actuating member is moved.

16. An automatic switch comprising in combination, a pivoted lever, a resilient contact blade carried thereon, a stationary contact cooperating with said contact blade to close an electric circuit, means biasing said lever to open circuit position, rst and second latches, and a condition responsive device which in response to a first condition value rotates said lever to closed circuit position and latches it in this position by said first latch while said second latch holds said resilient contact-blade in open circuit position, said condition responsive device in response to a second condition value tripping said second latch and on a return to said first condition value tripping said first latch.

17. An. automatic switch comprising in comy bination, a pivoted lever, a resilient contact blade said contact to prevent responsive device which in response to a rst condition value rotates said lever to closed circuit position and latches it in this position by said nrst latch while said second latch holds said resilient contact blade in open circuit position, said condition responsive device in response to a second condition value tripping said second latch and on a return to said rst condition value tripping said ilrst latch, and means for independently adjusting said condition values.

18. In a device of the character described, a switch member movable between open and closed positions, a iirst latching means to prevent movement of said switch to closed position, a second latching means to prevent movement of said switch to open position, a condition responsive device alternately cocking and tripping said two latching means to move said switch member between open and closed positions with a snap action, a support independent of the movable parts of said device, and means mounted on said'supvport for varying the difference between the condition values at which said switch is actuated to open and closed positions. 19. In a device of the character described, a

switch member movable between open and closed positions, a rst latching means to prevent movement of said switch to closedposition, a second latching means to prevent movement of said switch to open position, a condition responsive device alternately cooking and tripping said two .latching means to move said switch memberbetween open and closed positions .with a snap action, a support independent of the movable parts of said device, and meansI mountedon said support for varying the condition value at which said switch is actuated to one position independently of the condition value at which it is actuated to the other position.

20. In a device of the character described, a

rst member pivoted at a point between its ends,

a contact resiliently mounted upon one end thereof, 'a pair of latches adjacent the ends of said first member, one of said latches engaging said contact to prevent rotation thereof in one direction and the other of said latches engaging said rst member to prevent rotation thereof in the opposite direction, means biasing said memberin one direction, and means for moving said member in the opposite direction against said bias comprising, an elongated second member biased at its ends away from said iirst member,

means associated with the ends of said second member for actuating said latches, means as-l sociated with one end of said second member for moving said first member, and-,condition responsive means for moving said second member.k

21. In a device o` the character described, a rst member pivoted at a point between its ends, a contact resiliently` mounted upon one end thereof, a pair of latches adjacent the ends of said rst member, one of said latchesengaging rotation thereof in one direction and the other of said latches engaging said first member to prevent rotation thereof in the opposite direction, means biasing said member in one direction, and means for moving said member in the opposite direction against said bias.

ALBERT E. BAAK. 

